The incident was the second time in just over a year that Russian bombers have encroached on U.S. territory.

The nuclear-capable Tu-95 “Bear” bombers from Russia’s fleet did not enter sovereign U.S. or Canadian airspace.

“At approximately 10 a.m. eastern time, two Alaskan-based NORAD F-22 fighters intercepted and visually identified two Russian TU-95 ‘Bear’ long-range bomber aircraft flying in the Air Defense Identification Zone off the western coast of Alaska, north of the Aleutian Islands,” said Scott Miller, chief spokesman for Northern Command and the U.S.-Canada North American Aerospace Defense (NORAD) Command.

Miller confirmed that there was no unusual activity related to the Russian aircraft and no formal communication between the bombers and the United States’ F-22 jets.

He said the bombers were flying in international airspace and “flying according to international norms.” He reassured that NORAD continually monitors all air activity emanating from within and outside North American airspace.

The latest display of force by Moscow follows a recent theme of nuclear coercion aimed at the U.S.

“Putin’s Russia is in the nuclear intimidation business and is willing to burn to lot of unnecessary bomber fuel, not to mention the cost of refueling and additional maintenance hours resulting from the long flights, just to make that point,” said Mark Schneider, a former Pentagon strategic weapons expert. “Threatening people with nuclear weapons is Russia’s national sport.”

In May 2017, two Bear bombers and two Russian Su-35 Flanker fighter jets entered the ADIZ near Alaska, but left without incident.

On the recent flights, Schneider reaffirmed that the purpose of getting so close to the U.S. was specifically for intimidation and not any sort of training exercise.

“Irrespective of this, my perception is that the bomber ‘combat patrols,’ as Putin called them when he started them in 2007, are not realistic training for attack but rather nuclear intimidation flights,” Schneider said.

The Kremlin has taken an interest in the site in recent years. In 2012, Russian bombers simulated missile strikes on U.S. missile defense sites in Alaska as part of a major strategic nuclear forces exercise.